1. Field of the Invention
This invention relates to Striped Magnetoresistive (SMR) heads and Dual Stripe Magnetoresistive (DSMR) heads and more particularly to methods of manufacturing of exchange biasing configurations therefor, as well as devices manufactured by such methods.
2. Description of Related Art
As the continuous trend in magnetic recording requires increased area density, track widths of magnetic recording heads are being reduced. Commonly assigned U.S. patent application Ser. No. 09/182,775, filed Oct. 30, 1998 of Yimin Guo et al. for "Anti-Parallel Longitudinal Patterned Exchange Biased Dual Stripe Magnetoresistive (DSMR) Sensor Element and Method for Fabrication Thereof" describes a narrow track width DSMR head with dual sensors. The head, which increases signal amplitude is stabilized by anti-parallel biasing, i.e. with biasing which is parallel, but in the opposite directed or oriented. In such a biasing scheme, the magnetic centers of dual sensors self-align each other.
Accordingly, no track-offsetting is needed as disclosed in commonly assigned U.S. Pat. No. 5,783,460 of Han et al. for "Method of Making Self-Aligned Dual Stripe MagnetoResistive (DSMR) Head for High Density Recording" which shows a DSMR process using a lift off stencil to form a patterned dielectric layer edge. To achieve this quiescent biasing scheme, one can produce both sensors with Anti-Parallel EXchange-biasing (APEX) by means of exchange coupling between Anti-Ferro-Magnetic (AFM) and Ferro-Magnetic (FM) material.
U.S. Pat. No. 5,408,377 of Gurney et al. for "Magnetoresistive Sensor with Ferromagnetic Sensing Layer" shows a Ruthenium (Ru) AFM coupling film in a spin valve sensor.
U. S. Pat. No. 5,644,456 of Smith et al. for "Magnetically Capped Dual Magnetoresistive Reproduce Head" shows a cap layer in a DSMR that breaks exchange coupling between the magnetically permeable layer and MR elements.
U.S. Pat. No. 5,684,658 of Shi et al. for "High Track Density Dual Stripe Magnetoresistive (DMSR) Head" shows a DSMR having first and second anti-Ferro-Magnetic longitudinal biasing layers.
U.S. Pat. No. 5,731,936 of Lee et al. for "Magnetoresistive (MR) Sensor with Coefficient Enhancing that Promotes Thermal Stability" provides chromium based spacer layers for an MR layer of NiCr or NiFeCr compositions in place of Ta spacers to avoid a reported problem of degrading the magnetic moment of the MR stripe when high heat at the interface between the Ta spacer layer and the Permalloy (MR stripe) causing interdiffusion therebetween.
See Parkin, "Systematic Variation of the Strength and Oscillation Period of Indirect Magnetic Exchange Coupling through the 3d, 4d and 5d Transition Metals", Physical Review Letters Vol. 67, No. 25, pp. 3598-3601 (Dec. 16, 1991)
U.S. Pat. No. 5,766,780 of Huang et al. for "Reversed Order NiMn Exchange Biasing for Dual Magnetoresistive Heads" teaches a DSMR with a Mo layer as the conductor/seed layer on an alumina base coat. A NiMn exchange bias layer is formed on the Mo layer. A NiFe MR sensor layer is formed on the surface of the NiMn exchange bias layer.